Abstract

The unique and isolated nature of oxbow lakes from its parent river is reflected from studies on their water quality. This study was carried out to determine the water
quality of 4 oxbow lakes located along the Sg. Sugut, Beluran, 3 lakes located along the Sg. Padas, Beaufort and 3 lakes located along the Sg. Kinabatangan, Sandakan. Physical and chemical parameters of the water were studied during the wet and dry season from May 2003 until May 2005. Parameters measured were pH, dissolve oxygen (DO) and temperature, while those analysed in the laboratory were ammonium (NH4), nitrite (NO2), nitrate (NO3), total phosphorus (TP) and total suspended solid (TSS). Results from the study showed that pH ranged from 5.90 -8.44, dissolve oxygen 1.17 - 5.43 mg/L, temperature 28.50 - 29.90 Â°C, ammonium 0.05 - 2.54 mg/L, nitrite 0.006 - 0.184 mg/L, nitrate 0.10 - 15.30 mg/L, total phosphorus 0.01 - 0.94 mg/L and total suspended solid 4.3 - 192.0 mg/L.
Correlation analyses showed that Total Suspended Solids (r= 0.733, P<0.01), total phosphorus (r=0.553, P<0.01), dissolve oxygen (r=0.416, P<0.01), ammonium (r=0.206, P<0.01), nitrate (r=0.241, P<0.01), nitrite (r=-0.029, P<0.01), pH (r=-0.638, P<0.01) dan temperature (r=-0.831, P<0.01) at Sugut River were affected by seasonal changes. Most of the Oxbow lakes in Sg. Sugut, Sg. Kinabatangan and Sy.Padas are classified as moderate by polluted with WQI min=, 63.75 and are classified as mesotrofic and eutrophic lakes based on the Trofi Carlson Index. Management issues for sustainable conservation of the lakes are discussed with respect to the land-use and activities surrounding the lake.